Non Patent Literature 1 describes a method for measuring the temperature of brown adipose cells, as application of a non-contact temperature measurement method by near-infrared spectroscopy for an object of a small amount of aqueous solution. In the method described in this Literature, the brown adipose cells are irradiated with infrared light and the temperature of the brown adipose cells is measured based on the absorbance thereof. Specifically, by making use of the fact that the absorption spectrum of water molecules varies depending upon temperature, noradrenaline is added to cultured. BAT cells on a laboratory dish to activate them and changes in temperature of the brown adipose cells are measured.